Pfizer and Moderna vaccines are the protagonists of the vaccination campaign since it reached the population under 40 years of age. In fact, they are the only sera approved in minors and the ones that are more advanced in their authorization as a third dose. Thus, it is appropriate to remember how effective or side effects they have. The time between doses is 21 days for Pfizer and 28 for Moderna.

Pfizer and Moderna Vaccine Effectiveness
The Pfizer and Moderna vaccines, both based on messenger RNA, are 100% effective against developing severe disease. However, neither prevents infection. Therefore, those vaccinated must continue to respect preventive measures such as the safety distance or the mask.

Against the development of symptoms, the effectiveness of Pfizer is 95% and that of Moderna is 94.1% . However, this effectiveness drops for Pfizer to 88%, according to studies by Public Health England, with respect to the Delta variant.

Effectiveness over time: Pfizer generates fewer antibodies than Moderna
Research from the University of Virginia School of Medicine in the United States , recently presented, has revealed that antibody levels in recipients of Moderna’s vaccine were slightly higher than in recipients of Pfizer. The difference was mainly due to antibody levels in relatively older subjects.

The researchers caution against drawing conclusions about the effectiveness of vaccines based on the number of antibodies; since both vaccines have worked exceptionally after being administered to millions of people around the world. The new results are just one small piece in a much bigger puzzle, as scientists seek to determine whether a vaccine may be superior for certain demographics.

The Pfizer and Moderna vaccines use mRNA to teach the immune system how to defend against the COVID spike protein. However, the formulations of each vaccine are slightly different, and Moderna uses more mRNA than Pfizer. That prompted UVA scientists to seek to quantify and compare the resulting antibody responses.

Side effects of the Pfizer and Moderna vaccine

  1. The most frequent and common. The seventh pharmacovigilance report of the Spanish Agency for Medicines and Health Products (AEMPS) revealed the following adverse reactions: fever (37%), headache (27%), muscle aches (2nd%), pain in the area of vaccination (14%), malaise (12%), nausea (8%), arthralgia (8%), chills (8%), fatigue (8%), lymphadenopathy (7%).
  2. New or suspected side effects: during the application of the Pfizer vaccine in the general population, new side effects have been detected, some are already listed in the vaccine package insert and others are suspected:
  • Rash and pruritus : the Pfizer vaccine label and package leaflet already contains rash and pruritus (itching of the skin), as uncommon adverse reactions (occurring in less than 1 in 100 people). For their part, urticaria (raised, red, itchy skin rash) and angioedema (rapid swelling under the skin) have been updated as rare (less than 1 in 1,000 people) adverse reactions.
  • Localized inflammation with Pfizer in people who have previously received injections of dermal fillers in the face : the EMA has also concluded that it is possible that this effect is related to the vaccine, so it will be incorporated as a possible adverse reaction to the technical data sheet and the prospect.
  • Myocarditis and pericarditis : The EMA has concluded that after administration of the BioNTech / Pfizer vaccines, myocarditis and / or pericarditis may very rarely occur.

Side effects of Moderna’s vaccine

  1. The most frequent side effects. The seventh pharmacovigilance report of the AEMPS revealed the following: feverish state (50%), headache (30%), muscle aches (25%), pain in the vaccination area (19%), chills (11%) , malaise (13%), nausea (9%), arthralgia (8%), asthenia (6%).
  2. New or suspected side effects . The latest AEMPS report also reveals a series of new adverse reactions such as: diarrhea and immune thrombocytopenia, which causes bruising and bleeding. Another side effect, which is also reflected in the latest update of the Spanish vaccination strategy, is a series of late skin reactions near the injection site that occur about 7 days (between 2 and 12 days) after receiving the vaccine. Likewise, the EMA has also collected myocarditis and pericarditis.